This is the way I have been running two different overdrives for over 20 years on a dd/only vehicle now at 114 k miles in this form. I have a push/pull switch mounted conveniently on the dash using the 'T' throttle knob and position, to those of you that are familiar with Advance Design Chevrolet trucks. I am three on the tree and I have modified my home-bent shifting rods to accept heim joints for smooth shifting. Further modification was done to the shifters in the engine compartment, I shortened them and I used the shortest transmission shifter arms to achieve smaller radii. By doing this my shifting is precise, short and crisp. The first OD I had was a Muncie 319 with the non-synchro 1st gear. The OD I am using presently is the Saginaw version, 1969 vintage with all synchro gears. I drive a '49 Chevrolet half ton with a '56 235, Edelbrock intake with two X two Carter-Webers, Fentons, X-pipe, 2- 22" cherry bombs (that I doubt have any damping materiel remaining after 20 years). I recently achieved 17.8 mpg on a random tankful of fuel on a 1200 mile round trip. I find that I enjoy driving at 72 mph as the vibration/harmonics seem to be in a great 'sweet spot'. Squirrel said something that was spot on so I'll have to walk back to see it. Yes, he mentioned how the Overdrive ON Lamp functions... the way I have it wired above, the light comes on when the governor reaches the cut-in speed, for me ~30 mph. An interesting side note to this '69 OD governor is that it has two adjustments where a guy could actually adjust the cut-in point to achieve a 6 speed! I actually had her set up this way for a couple years... 1st, 1st overdrive, 2nd, 2nd overdrive, 3rd, 3rd overdrive! A true 6 speed. You should have seen friends faces when I 'rowed through the gears'! Hahahahaha. They are super transmissions, but alas I am a driver not a hot-rodder, but 114 k is a testimony to their durability I would think, of course your results may vary. My truck no longer has the limiting 4.11 gears of the torque tube. I retained the '49 axle housing, burned off the articulating closed driveshaft axle mounts and also re used the '49 axles. With welded on saddles and a '57 truck 3.90 rear, a driveshaft was fitted to the overdrive. For you math majors that is .70 Overdrive X 3.90 Differential = 2.73, 3rd gear in overdrive. I sport 1936-1937 17" Chevrolet artillery wheels and with Michelin 235 75R 17 tires, which, at 30.88" are a street legal 'poor man's overdrive'. This combination is excellent gearing for the rolling piedmont foothills of central Virginia.